Refrigeration cycle device and compressor used in same

ABSTRACT

A refrigeration cycle device according to the present invention includes a compressor having a first compression chamber and a second compression chamber, a condenser, a decompressor, an evaporator, an injection path configured to introduce intermediate pressure refrigerant, a communication passage configured to introduce intermediate pressure refrigerant compressed in the first compression chamber to the second compression chamber, and a switch element configured to selectively make the second compression chamber communicate with the evaporator or make the second compression chamber communicate with the communication passage. The injection path introduces the intermediate pressure refrigerant to the second compression chamber. Single-stage compressing operation is performed when the second compression chamber is communicated with the evaporator, and two-stage compressing operation is performed when the second compression chamber is communicated with the communication passage.

TECHNICAL FIELD

The present invention relates to a refrigeration cycle device and a compressor used in the same.

BACKGROUND ART

FIG. 6 is a diagram illustrating a refrigeration cycle configured by compressor 101, condenser 102, evaporator 103, decompressors 104, injection pipe 105, and gas-liquid separator 106. In the refrigeration cycle, a gas phase component and a liquid phase component of intermediate pressure refrigerant are separated by using gas-liquid separator 106 to perform gas injection. Conventionally, in order to reduce power consumption and improve capability of the refrigeration cycle, a refrigeration cycle device has been proposed that injects intermediate pressure gas refrigerant into a compressor. For example, Patent Literature 1 discloses a rotary compressor equipped with back flow suppressive means for suppressing back flow of gas refrigerant in a compression chamber when gas refrigerant that has taken out from gas-liquid separator 106 is injected in the working compression chamber. Furthermore, Patent Literature 2 discloses a rotary type two-stage compressor that performs gas injection with respect to an intermediate pressure region of two-stage compression.

However, like Patent Literature 1, when gas injection is performed with respect to the working compression chamber, the pressure in the compression chamber is largely fluctuated from low pressure to high pressure at the cycle of an operation frequency, causing a problem to be described below. That is, when the pressure of an injection pipe outlet becomes higher than an injection gas pressure, the refrigerant in the compression chamber may disadvantageously flow back from an injection port. To solve the problem, Patent Literature 1 discloses provisions such as providing a check valve to prevent back flow, but the check valve can block original flow of the injection. Furthermore, even when back flow itself can be suppressed, injection to the compression chamber whose pressure fluctuates becomes intermittent, so that pulsation of refrigerant pressure in the injection pipe becomes large, disadvantageously causing noise or vibration.

On the other hand, like Patent Literature 2, when injection is performed in the intermediate pressure region of the two-stage compression, injection is performed to a stable pressure region, which solves the above problems, making it possible to perform gas injection of a continuously stable amount. In the tow-stage compression system, under the operating condition in which the pressure difference between low pressure and high pressure is large, leakage or the like of refrigerant due to the pressure difference becomes small as compared with a single-stage compression system, making it possible to exert high efficiency capability. However, under the operation condition with a low load in which the pressure difference is small, the two-stage compression system has a problem in that its efficiency is lowered as compared with the single-stage compression system due to slide loss or the like. Furthermore, substantive compressor suction volume is limited to the volume of the compression chamber on the side on which low pressure refrigerant is suctioned, requiring grow in size of the compressor in order to exert a desired refrigerating or heating capability under low differential pressure operation conditions in which injection effect is small.

CITATION LIST Patent Literature

PTL 1: Japanese Patent No. 3718964

PTL 2: Japanese Patent No. 4719432

SUMMARY OF THE INVENTION

The present invention is to solve the above problems, and provides a refrigeration cycle device that switches to injection operation of a two-stage compression system during high load operation, for example, during low outdoor air temperature while employing a single-stage compression system that exerts high efficiency capability during normal operation. This provides a refrigeration cycle device that exerts a high capability.

That is, a refrigeration cycle device according to the present invention includes a compressor including a first compression chamber and a second compression chamber that are independent, a condenser, a decompressor, an evaporator, an injection path configured to introduce intermediate pressure refrigerant decompressed by the decompressor, a first suction path configured to introduce low pressure refrigerant from the evaporator to the first compression chamber, and a second suction path configured to introduce low pressure refrigerant from the evaporator to the second compression chamber. The refrigeration cycle device further includes a communication passage configured to introduce intermediate pressure refrigerant compressed in the first compression chamber to the second compression chamber, and a switch element configured to selectively make the second compression chamber communicate with the evaporator or make the second compression chamber communicate with the communication passage. The injection path introduces the intermediate pressure refrigerant to the second compression chamber. The refrigerant is compressed in the first compression chamber and the second compression chamber independently when the second compression chamber is communicated with the evaporator, and refrigerant compressed in the first compression chamber is further compressed in the second compression chamber when the second compression chamber is communicated with the communication passage.

This makes it possible to exert high heating capability utilizing injection effect by two-stage injection operation that does not cause pulsation of the injection pipe under the operating conditions in which pressure difference is large such as operation at a low outdoor air temperature as a refrigeration cycle device that injects intermediate pressure gas refrigerant. This also enables power consumption suppressed high efficient operation by making each of the two compression chambers perform single-stage compression from a low pressure to a high pressure during low load and low differential pressure operation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a compressor and a refrigeration cycle during single-stage compressing operation in a refrigeration cycle according to the present invention.

FIG. 2 is a diagram illustrating the compressor and the refrigeration cycle during two-stage compressing operation in the refrigeration cycle according to the present invention.

FIG. 3 is an enlarged view of a compression mechanism portion structuring the refrigeration cycle according to the present invention.

FIG. 4 is a plan view of a compression chamber of a rotary compressor structuring the refrigeration cycle according to the present invention.

FIG. 5 is a diagram illustrating a relation between a compression chamber volume ratio and an injection ratio in the refrigeration cycle according to the present invention.

FIG. 6 is a diagram illustrating a conventional injection refrigeration cycle using a gas-liquid separator.

DESCRIPTION OF EMBODIMENT

A first aspect of the present disclosure includes a compressor including a first compression chamber and a second compression chamber that are independent, a condenser, a decompressor, an evaporator, an injection path configured to introduce intermediate pressure refrigerant decompressed by the decompressor, a first suction path configured to introduce low pressure refrigerant from the evaporator to the first compression chamber, and a second suction path configured to introduce low pressure refrigerant from the evaporator to the second compression chamber. The refrigeration cycle device further includes a communication passage configured to introduce intermediate pressure refrigerant compressed in the first compression chamber to the second compression chamber, and a switch element configured to selectively make the second compression chamber communicate with the evaporator or make the second compression chamber communicate with the communication passage. The injection path introduces the intermediate pressure refrigerant to the second compression chamber. The refrigerant is compressed in the first compression chamber and the second compression chamber independently when the second compression chamber is communicated with the evaporator, and refrigerant compressed in the first compression chamber is further compressed in the second compression chamber when the second compression chamber is communicated with the communication passage.

This makes it possible to exert high heating capability utilizing injection effect by two-stage injection operation that does not cause pulsation of the injection pipe under the operating conditions in which pressure difference is large such as operation at a low outdoor air temperature. This also enables power consumption suppressed high efficient operation by making each of the two compression chambers perform single-stage compression from a low pressure to a high pressure during low load and low differential pressure operation.

In a second aspect, in the refrigeration cycle device according to the first aspect, the second suction path has a connection part connecting with the injection path on a downstream side of the switch element.

This makes overheated refrigerant compressed in the first compression chamber be mixed with intermediate pressure refrigerant, which is small in degree of superheat, transmitted from injection pipe till the overheated refrigerant is introduced in the second compression chamber, when two-stage compressing operation is performed. This makes it possible to reduce degree of superheat of the refrigerant introduced in the second compression chamber, making it possible to improve compression efficiency in the second compression chamber. Furthermore, when single-stage compressing operation is performed, making the pressure of the refrigerant flowing in the injection pipe be a substantively low pressure state and using the injection pipe as a bypass circuit of the refrigerant passing through the evaporator become possible, making it possible to reduce the gas refrigerant flowing in the evaporator. This makes it possible to yield efficiency improvement effect of the evaporator, making it possible to improve refrigeration cycle efficiency and capability.

In a third aspect, in the refrigeration cycle device according to the first aspect, a volume of the first compression chamber and a volume of the second compression chamber are equal. Note that a volume ratio only needs to be substantially equal and may have a difference of about ±10%.

This makes it possible to make the sizes and weights of eccentric rotation series members such as a shaft eccentric shaft and a piston equal, making it possible to manufacture the compressor with a low price.

In a fourth aspect, in the refrigeration cycle device according to the first aspect, the compressor is provided around a shaft and has two eccentric shafts each performing eccentric rotation, and phases of the two eccentric shafts are deviated by 180 degrees.

This makes it possible to structure two compression mechanisms without deviating the gravity center of the rotation member with respect to a shaft axis direction, making it possible to suppress vibration of the compressor. Furthermore, allocation ratios of compression power become equal, making it possible to perform efficient compressing operation. Note that “deviation by 180 degrees” includes the case of “deviation by substantially 180 degrees”.

In a fifth aspect, in the refrigeration cycle device according to the second aspect, the second suction path has an upward gradient part between the connection part and the second compression chamber.

This makes the intermediate pressure overheated gas refrigerant introduced from the first compression chamber be preferentially introduced to the second compression chamber even when liquid refrigerant is flown from the injection pipe when the two-stage injection operation is performed. Liquid component refrigerant that is large in its specific gravity is evaporated by heat exchange with overheated gas refrigerant without being introduced in the second compression chamber. This makes it possible to keep lubrication of the compressor good and efficiently perform the two-stage compressing operation.

In a sixth aspect, in the refrigeration cycle device according to the first aspect, inverter operation to arbitrarily change a rotation number of the compressor is performed.

This makes it possible to perform continuous high efficiency operation with respect to a wide range capability zone from small capability to large capability, and to provide a large capability operation in which the injection effect and high speed operation are combined during a low outside air temperature.

A seventh aspect provides the compressor used in the refrigeration cycle device according to any one of the first aspect to the sixth aspect.

Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the following exemplary embodiment.

First Exemplary Embodiment

FIG. 1 is a refrigeration cycle diagram during single-stage compressing operation according to an exemplary embodiment of the present invention. FIG. 2 is a refrigeration cycle diagram during two-stage compressing operation according to the exemplary embodiment. FIG. 3 is an enlarged view of a compression mechanism portion according to the exemplary embodiment. FIG. 4 is a plan view of a compression chamber of a rotary compression mechanism according to the exemplary embodiment.

As illustrated in FIGS. 1 and 2, a refrigeration cycle device of the exemplary embodiment includes compressor 1, condenser 2, evaporator 3, decompressors 4, injection pipe 5, and gas-liquid separator 6.

A main body of compressor 1 includes, in sealed vessel 11, motor 12, first compression mechanism 20 structuring first compression chamber 21, second compression mechanism 30 structuring second compression chamber 31, and shaft 13. Motor 12 is disposed above first compression mechanism 20 and second compression mechanism 30. First compression mechanism 20, second compression mechanism 30, and motor 12 are coupled with shaft 13. Terminal 14 for supplying electric power to motor 12 is provided at an upper portion of sealed vessel 11. Oil storage part 15 for retaining lubricant is formed at the bottom of sealed vessel 11. The main body of the compressor has a structure of a so-called hermetic compressor.

Each of first compression mechanism 20 and second compression mechanism 30 is a positive displacement fluid mechanism.

First compression mechanism 20 includes first cylinder 25, first piston 26, first vane 27, first spring 29, first frame 60, and partition plate 40. First piston 26 is disposed inside first cylinder 25. First piston 26 is fitted with first eccentric shaft 13 a of shaft 13. First compression chamber 21 is formed between the outer periphery of first piston 26 and the inner periphery of first cylinder 25. First vane groove 28 is formed in first cylinder 25. First vane 27 and first spring 29 are housed in first vane groove 28. The tip of first vane 27 is in contact with the outer periphery of the first piston. First vane 27 is pushed toward first piston 26 by first spring 29.

First frame 60 is disposed at the lower face of first cylinder 25, and partition plate 40 is disposed at the upper face of first cylinder 25. First cylinder 25 is sandwiched between first frame 60 and partition plate 40. In first compression chamber 21, a first suction chamber and a first compression-discharge chamber are formed by being partitioned by first vane 27.

Second compression mechanism 30 includes second cylinder 35, second piston 36, a second vane (not shown), a second spring (not shown), second frame 70, and partition plate 40. Second cylinder 35 is concentrically arranged with respect to first cylinder 25. Second piston 36 is disposed inside second cylinder 35. Second piston 36 is fitted with a second eccentric shaft (not shown) of shaft 13. Second compression chamber 31 is formed between the outer periphery of second piston 36 and the inner periphery of second cylinder 35. A second vane groove is formed in second cylinder 35. A second vane and a second spring are housed in the second vane groove. The tip of the second vane is in contact with the outer periphery of the second piston. The second vane is pushed toward second piston 36 by the second spring. Second frame 70 is disposed at the upper face of second cylinder 35, and partition plate 40 is disposed at the lower face of the second cylinder 35. Second cylinder 35 is sandwiched between second frame 70 and partition plate 40. In second compression chamber 31, a second suction chamber and a second compression-discharge chamber are formed by being partitioned by the second vane.

Furthermore, the eccentricity direction of first eccentric shaft 13 a is deviated from the eccentricity direction of second eccentric shaft 13 b by 180 degrees. That is, the phase of first piston 26 is deviated from the phase of second piston 36 by 180 degrees in a rotation angle of shaft 13.

Furthermore, first discharge space 24 in which the refrigerant compressed by first compression chamber 21 is discharged is provided in first frame 60. The refrigerant (working fluid) compressed by first compression chamber 21 is introduced into first suction chamber 21 a of first compression chamber 21 through first suction path 96. The refrigerant discharged from first compression-discharge chamber 21 b of first compression chamber 21 is flown into first discharge space 24 from first discharge hole 22 formed in first frame 60.

Furthermore, first check valve 23 is provided at first discharge hole 22. First check valve 23 prevents refrigerant from being flown from first discharge space 24 to first compression chamber 21. Furthermore, single-stage compression communication passage 91 and single-stage compression discharge hole 92 are formed between first discharge space 24 and sealed vessel 11. Single-stage compression discharge hole 92 is formed at second frame 70. Single-stage compression communication passage 91 and single-stage compression discharge hole 92 make first discharge space 24 communicate with an inside of sealed vessel 11. Furthermore, third check valve 93 is provided at single-stage compression discharge hole 92. Third check valve 93 prevents refrigerant from being flown from the inside of sealed vessel 11 to first ejection space 24.

The refrigerant compressed in second compression chamber 31 is introduced into a second suction chamber (not shown) of second compression chamber 31 through second suction path 97. The refrigerant discharged from the second compression-discharge chamber (not shown) of a second compression chamber 31 is introduced inside sealed vessel 11 from second discharge hole 32. Second discharge hole 32 is formed at second frame 70.

Second check valve 33 is provided at second discharge hole 32. Second check valve 33 prevents refrigerant from being flown from the inside of sealed vessel 11 to second compression chamber 31.

Two-stage compression communication passage 94 makes first discharge space 24 connect with switch valve 95 (control element), and makes first discharge space 24 communicate with second suction path 97 (FIG. 2) or blocks the communication (FIG. 1) depending on the state of switch valve 95.

Discharge path 90 penetrates an upper portion of sealed vessel 11. Discharge path 90 introduces compressed refrigerant outside sealed vessel 11. Discharge path 90 is connected to condenser 2 to supply high-pressure refrigerant to condenser 2.

First suction path 96 (first connection pipe 53) connects first compression mechanism 20 and accumulator 50 and introduces refrigerant to be compressed from accumulator 50 to first compression chamber 21 of first compression mechanism 20.

Second suction path 97 connects second compression mechanism 30 and switch valve 95 serving as a control element. To switch valve 95, an end of second suction path 97, an end of second connection pipe 54 connected with accumulator 50, and an end of two-stage compression communication passage 94 are connected. Switch valve 95 selectively makes one of second connection pipe 54 and two-stage compression communication passage 94 communicate with second suction path 97 and blocks the path between the other one and second suction path 97. In other words, switch valve 95 selectively makes second compression chamber 31 communicate with evaporator 3 or makes second compression chamber 31 communicate with two-stage compression communication passage 94.

Injection pipe 5 is connected at an upper portion of second suction path 97 connecting second compression mechanism 30 and switch valve 95. Second suction path 97 is equipped with connection part 80 with injection pipe 5 on the downstream side of switch valve 95. Second suction path 97 joins the gas refrigerant introduced from gas-liquid separator 6 through injection pipe 5 and the refrigerant introduced from switch valve 95 and introduces the gas refrigerant and the refrigerant to second compression mechanism 30. Second suction path 97 has upward gradient part 97 a between connection part 80 of injection pipe 5 and second compression mechanism 30. This preferentially introduces gas refrigerant relatively light in specific gravity to second compression mechanism 30 when the joined refrigerant is watery refrigerant including liquid component. Moreover, liquid storage part 97 b may be provided so that liquid refrigerant exchanges heat with overheated gas refrigerant to be evaporated.

The refrigerant condensed in condenser 2 is decompressed in decompressor 4. Gas-liquid separator 6 separates some evaporated gas refrigerant and liquid refrigerant. The separated liquid refrigerant further passes through decompressor 4 and is introduced to evaporator 3 as low-pressure refrigerant. In contrast, gas refrigerant separated by gas-liquid separator 6 passes through injection pipe 5 and is joined with the refrigerant introduced from any one of second connection pipe 54 and two-stage compression communication passage 94 at second suction path 97, and is introduced to second compression mechanism 30. In the present invention, since injection gas is introduced to a stable pressure region, back flow does not occur in injection pipe 5. However, means for adjusting or stopping injection pressure may be provided by providing a close valve or a metering valve at injection pipe 5.

To evaporator 3, the refrigerant decompressed to a low pressure by decompressor 4 is introduced, and liquid refrigerant is evaporated by thermal exchange to be discharged as gas refrigerant. The discharged refrigerant is introduced to accumulator 50 with liquid refrigerant that has failed to be evaporated in evaporator 3.

Accumulator 50 includes accumulation vessel 51, introduction pipe 52, first connection pipe 53, and second connection pipe 54. Accumulation vessel 51 has an internal space capable of retaining liquid refrigerant and gas refrigerant. Introduction pipe 52 is provided at an upper portion of accumulation vessel 51. Introduction pipe 52 is connected with evaporator 3 to supply low pressure refrigerant. First connection pipe 53 and second connection pipe 54 penetrate bottom portions of accumulation vessel 51 and are opened to the inner space of accumulation vessel 51. Note that another member such as a baffle may be provided inside accumulation vessel 51 to prevent liquid refrigerant from being flown into first connection pipe 53 and second connection pipe 54 from introduction pipe 52. Alternatively, first connection pipe 53 and the second connection pipe may be directly connected with introduction pipe 52 depending on the type of compressor 1.

The exemplary embodiment makes it possible to switch between the refrigeration cycle operation in which the single-stage compressing operation is simultaneously performed by the two compression mechanisms and the refrigeration cycle operation in which the two-stage compressing operation is performed by the two compression mechanisms with the injection of an intermediate pressure, by using switch valve 95. Hereinafter, the description will be specifically described.

First, the case of performing the single-stage compressing operation during low differential pressure in which pressure difference between high pressure and low pressure is small will be described.

As illustrated in FIG. 1, second suction path 97 and second connection pipe 54 are connected by switch valve 95. In contrast, second suction path 97 and two-stage compression communication passage 94 are blocked. In this case, first compression mechanism 20 and second compression mechanism 30 are connected to accumulator 50, so that first compression mechanism 20 and second compression mechanism 30 are connected in parallel.

The flow of refrigerant in this case will be specifically described.

The refrigerant suctioned from first suction path 96 is compressed by first compression mechanism 20, and discharged in first discharge space 24 through first discharge hole 22. On the other hand, two-stage compression communication passage 94 communicating with first discharge space 24 is blocked by switch valve 95. Consequently, the pressure in first discharge space 24 increases to the level equal to the pressure inside sealed vessel 11. As a result, the refrigerant discharged in first discharge space 24 passes through single-stage compression communication passage 91 and single-stage compression discharge hole 92, opens third check valve 93, and is discharged inside sealed vessel 11. Furthermore, since second suction path 97 is connected with accumulator 50 via switch valve 95, the refrigerant suctioned from second suction path 97 is compressed by second compression mechanism 30, and is discharged inside sealed vessel 11 through second discharge hole 32. In this context, the refrigerants compressed by respective first compression mechanism 20 and second compression mechanism 30 join inside sealed vessel 11 to be introduced outside sealed vessel 11 through discharge path 90.

Herein, given that the suction volume of first compression mechanism 20 is V1 and the suction volume of second compression mechanism 30 is V2, the suction volume during single-stage compressing operation becomes V1+V2. In the exemplary embodiment, by making V1 and V2 substantially same, workloads of the respective two compression mechanisms are equalized, enabling high efficiency compression behaviors. Furthermore, injection pipe 5 is connected to second suction path 97, making it possible to use injection pipe 5 as a bypass of evaporator 3. That is, by adjusting decompressor 4, the pressure of gas-liquid separator 6 is lowered to be a low pressure to make only gas refrigerant having no latent heat be bypassed from injection pipe 5 to second compression mechanism 30. This makes it possible to preferentially transmit the liquid refrigerant that essentially needs to be introduced to evaporator 3, also making it possible to perform higher efficient operation by pressure loss reduction effect in evaporator 3.

Next, the case of performing two-stage injection compressing operation during high differential pressure in which pressure difference between high pressure and low pressure is large will be described.

As illustrated in FIG. 2, second suction path 97 and two-stage compression communication passage 94 are connected by switch valve 95, and connection between second suction path 97 and second connection pipe 54 is blocked. In this case, only the first suction path is connected to accumulator 50, so that first compression mechanism 20 and second compression mechanism 30 are connected in series.

The flow of refrigerant in this case will be specifically described.

The refrigerant suctioned from first suction path 96 is compressed by first compression mechanism 20, and discharged in first discharge space 24 through first discharge hole 22. Herein, two-stage compression communication passage 94 communicating with first discharge space 24 is connected to second suction path 97 via switch valve 95. Consequently, the refrigerant discharged in first discharge space 24 joins the refrigerant introduced from injection pipe 5 in second suction path 97, and compressed by second compression mechanism 30. The refrigerant compressed by second compression mechanism 30 is discharged inside sealed vessel 11 through second discharge hole 32. Herein, first compression mechanism 20 and second compression mechanism 30 are connected in series, so that the pressure in first discharge space 24 becomes an intermediate pressure lower than the discharge pressure of second compression mechanism 30. Consequently, third check valve 93 is closed by the pressure difference between first discharge space 24 and the inside of sealed vessel 11. As a result, all of the refrigerant compressed by first compression mechanism 20 is flown into second compression mechanism 30. Furthermore, the refrigerant compressed by second compression mechanism 30 is discharged inside sealed vessel 11, and introduced outside the sealed vessel through discharge path 90.

In the ratio between gas refrigerant and liquid refrigerant among the refrigerant separated by the gas-liquid separator, gas component increases as the pressure difference between high pressure and low pressure of the refrigeration cycle becomes larger. In the case of the conventionally proposed two-stage dedicated compressor, securing sufficient gas injection refrigerant is impossible under low load conditions where pressure difference is small, so that it is preferable to preliminarily design the heights of first cylinder 25 and second cylinder 35 to be different in order to perform the two-stage compressing operation. As a result, suction volume V1 of first compression mechanism 20 becomes larger than suction volume V2 of second compression mechanism 30. However, in the exemplary embodiment, the two-stage compressing operation is limited only to a high differential pressure condition that allows injection gas to be sufficiently secured, enabling suction volume V1 of first compression mechanism 20 to be substantially equal to suction volume V2 of second compression mechanism 30.

This enables the heights of first cylinder 25 and second cylinder 35 to be equal to thereby make the shapes and heights of first piston 26 and second piston 36 equal. Likewise, this enables the shapes and heights of first eccentric shaft 13 a and the second eccentric shaft to be equal. As a result, deviating the phases of first eccentric shaft 13 a and the second eccentric shaft by 180 degrees makes it possible to structure two compression mechanisms without deviating the gravity center of a rotation member from the shaft center, making it possible to provide low vibration from a low speed to a high speed.

Furthermore, the volume ratio of second compression mechanism 30 can be made larger than that of the conventional two-stage dedicated compressor, making it possible to cope with refrigeration recycle operation with a higher injection rate during high differential pressure operation. This makes it possible to sufficiently exert ability improvement effects during low outside air temperature operation. This point will be described below in detail.

In the case of the conventional two-stage dedicated compressor, the volume of the second compression chamber needs to be made smaller than the volume of the first compression chamber to keep the two-stage compressing operation in consideration of the need to perform operation with no injection during low load operation. The graph illustrated in FIG. 5 illustrates the volume ratio of the second compression chamber with respect to the first compression chamber and the maximum ratio of gas injection refrigerant capable of being passed through the injection pipe among the refrigerant in the refrigeration cycle (called injection ratio) when outside air temperature is assumed to be −30° C. The configuration of the present invention makes it possible to increase the volume ratio of second compression mechanism 30 as compared with the configuration of the conventional two-stage dedicated compressor in which the volume ratio of the second compression chamber is small, making it possible to increase the injection ratio. This makes it possible to exert greater injection effect during low outside air temperature to provide high capability.

Next, separation of oil from refrigerant will be described.

The compressor of a high pressure type in which refrigerant is once discharged inside sealed vessel 11, passed through discharge path 90, and thereafter introduced outside sealed vessel 11 typically has oil storage part 15 in the sealed vessel. This is to prevent leakage of lubricant of each slide portion of the compression mechanism and refrigerant being compressed. Compressor 1 used in the refrigeration cycle device according to the exemplary embodiment also has oil storage part 15 to prevent leakage of the lubricant of each slide portion of the compression mechanism and the refrigerant being compressed.

Some of the oil introduced in the compression mechanism portion is mixed with refrigerant during compression and the refrigerant and the oil are discharged together inside sealed vessel 11. Oil, which is larger in specific gravity than that of refrigerant, of the fluid that is mixture of the refrigerant and the oil discharged inside sealed vessel 11 is separated from the refrigerant by centrifugal force and gravitational force while being moved upward at the vicinity of motor 12 or inside the sealed vessel 11. The separated oil returns to oil storage part 15 inside sealed vessel 11. The above behavior enables the high-pressure type compressor according to the exemplary embodiment capable of separating the oil from the refrigerant in sealed vessel 11 to reduce the amount of oil introduced outside sealed vessel 11 through discharge path 90, preventing condenser 2 and evaporator 3 from being lowered in their efficiency. This makes it possible to provide a refrigeration cycle device operable with high efficiency.

According to the present exemplary embodiment, in both of the single-stage compressing operation and the two-stage injection compressing operation, all refrigerant is introduced outside sealed vessel 11 through discharge path 90 after discharged inside sealed vessel 11. This enables the refrigerant to be discharged outside sealed vessel 11 after refrigerant and oil are fully separated inside sealed vessel 11, preventing condenser 2 and evaporator 3 from being lowered in their efficiency. This also makes it possible to reduce oil to be taken out from sealed vessel 11, making it possible to stably secure oil in oil storage part 15 to prevent seizure and abnormal wear of the components of the compression mechanism portion.

Note that in the exemplary embodiment, first compression mechanism 20 is disposed on the far side of motor 12 and second compression mechanism 30 is disposed on the near side of the motor 12. That is, motor 12, second compression mechanism 30, and first compression mechanism 20 are aligned in this order along the axis direction of shaft 13. This order makes it possible to make first discharge space 24 wide without being interfered by motor 12 and the like as illustrated in FIGS. 1 and 2, making it possible to sufficiently yield refrigerant pulsation lowering effect in first discharge space 24. This makes it possible to further reduce pressure pulsation in second suction path 97 connected with injection pipe 5, making it possible to reduce vibration and noise of refrigerant pipe.

Note that first vane 27 and the second vane may be unified with first piston 26 and second piston 36, respectively. That is, the vane and the piston may be a so-called swing piston. Furthermore, first piston 26 and first vane 27 may be jointed with second piston 36 and the second vane.

Furthermore, the effects of the present invention can be also obtained by other positive-displacement compression mechanism such as a scroll compression system, a screw compression system, and the like, non positive-displacement compression mechanism such as a turbo type, and a combination (not shown) of the different compression systems without using the rotary compression system for first compression mechanism 20 and second compression mechanism 30.

Motor 12 is structured by stator 12 a and rotor 12 b. Stator 12 a is fixed to the inner periphery of sealed vessel 11. Rotor 12 b is fixed to shaft 13 and rotates with shaft 13. By the motor 12, first piston 26 and second piston 36 are moved inside first cylinder 25 and second cylinder 35, respectively. As motor 12, motors that can change rotation numbers thereof such as an interior permanent magnet synchronous motor (IPMSM) and a surface permanent magnet synchronous motor (SPMSM) can be used.

Controller 8 adjusts the rotation number of motor 12, that is, a rotation number of compressor 1 by controlling inverter 7. As controller 8, a digital signal processor (DSP) can be used including an A/D conversion circuit, an input-output circuit, an arithmetic circuit, a storage device, and the like.

INDUSTRIAL APPLICABILITY

The present invention is useful for a refrigeration cycle device that can be used in an electrical product such as a hydronic heater, an air conditioner, and a hot water dispenser in which their evaporator is used under a low temperature environment.

REFERENCE MARKS IN THE DRAWINGS

-   -   1 compressor     -   2 condenser     -   3 evaporator     -   4 decompressor     -   5 injection pipe     -   6 gas-liquid separator     -   7 inverter     -   7 controller     -   8 sealed vessel     -   11 motor     -   12 a stator     -   12 b rotor     -   13 shaft     -   13 a first eccentric shaft     -   13 b second eccentric shaft     -   14 terminal     -   15 oil storage part     -   20 first compression mechanism     -   21 first compression chamber     -   21 a first suction chamber     -   21 b first compression-discharge chamber     -   22 first discharge hole     -   23 first check valve     -   24 first discharge space     -   25 first cylinder     -   26 first piston     -   27 first vane     -   28 first vane groove     -   29 first spring     -   30 second compression mechanism     -   31 second compression chamber     -   32 second discharge hole     -   33 second check valve     -   35 second cylinder     -   35 second piston     -   36 second vane groove     -   38 partition plate     -   40 accumulator     -   51 accumulation vessel     -   52 introduction pipe     -   53 first connection pipe     -   54 second connection pipe     -   60 first frame     -   70 second frame     -   80 connection part     -   90 discharge path     -   91 single-stage compression communication passage     -   92 single-stage compression discharge hole     -   93 third check valve     -   94 two-stage compression communication passage     -   95 switch valve (control element)     -   96 first suction path     -   97 second suction path     -   97 a upward gradient part     -   97 b liquid storage part 

1. A refrigeration cycle device comprising: a compressor including a first compression chamber and a second compression chamber that are independent; a condenser; a decompressor; an evaporator; an injection path configured to introduce intermediate pressure refrigerant decompressed by the decompressor; a first suction path configured to introduce low pressure refrigerant from the evaporator to the first compression chamber; a second suction path configured to introduce low pressure refrigerant from the evaporator to the second compression chamber; a communication passage configured to introduce intermediate pressure refrigerant compressed in the first compression chamber to the second compression chamber; and a switch element configured to selectively make the second compression chamber communicate with the evaporator or make the second compression chamber communicate with the communication passage, wherein the injection path introduces the intermediate pressure refrigerant to the second compression chamber, the refrigerant is compressed in the first compression chamber and the second compression chamber independently when the second compression chamber is communicated with the evaporator, and refrigerant compressed in the first compression chamber is further compressed in the second compression chamber when the second compression chamber is communicated with the communication passage.
 2. The refrigeration cycle device according to claim 1, wherein the second suction path has a connection part connecting with the injection path on a downstream side of the switch element.
 3. The refrigeration cycle device according to claim 1, wherein a volume of the first compression chamber and a volume of the second compression chamber are equal.
 4. The refrigeration cycle device according to claim 1, wherein the compressor is provided around a shaft and has two eccentric shafts each performing eccentric rotation, and phases of the two eccentric shafts are deviated by 180 degrees.
 5. The refrigeration cycle device according to claim 2, wherein the second suction path has an upward gradient part between the connection part and the second compression chamber.
 6. The refrigeration cycle device according to claim 1, wherein inverter operation to arbitrarily change a rotation number of the compressor is performed.
 7. A compressor being the compressor included in the refrigeration cycle device according to any one of claims 1 to
 6. 